1. Field of the Invention
The present invention relates to jewelry and gemstones and more particularly to an apparatus for mounting gemstones in jewelry settings. The present invention further relates to apparatus for forming an inset seat in a prong type jewelry setting which receives a gemstone and then swaging the ends of the prongs over the girdle of the stone without repositioning the setting relative to the mounting apparatus.
2. Background
Many gemstones are secured in place in jewelry settings using formed meal or metal projections that extend over the top of the stone table to hold the stone against a seat comprising a recessed edge or projection within a mounting structure.
A typical stone mounting or setting structure for precious or semi-precious stones such as diamonds, is a solitary tiffany setting or cage which comprises a series of spaced apart supports commonly known as "prongs". Standard stone settings use 4 or 6 prongs, although the number varies according to the size of the setting or gemstone. The prongs generally extend up and outward at an angle from a mounting surface, such as a ring or a stud base, and are grouped symmetrically about a central mounting location. In some jewelry settings the prongs extend straight up from a mounting surface or circular ring in a right circular cylindrical pattern. In either case, when viewed from above the top of the prongs form a circular pattern.
In order to form a seat or inset resting edge for the stone a jeweler, stone setter, or technicial uses deburring, or cutting tools to remove material from the inner edge of the ends of the prongs. Enough material is removed from each prong to form an inset edge large enough to accommodate the stone girdle dimensions but not enough to make the stone loose or the support prongs weak.
The seat preparation is generally performed using a hand held rotary power tool, such as an electrically powered drill head or chuck, to drive a deburring or cutting tool. An exemplary deburring tool is disclosed in U.S. Pat. No. 980,060, issued Dec. 27, 1910 to J. J. Buser. Operation of such tools requires a great deal of skill and time to create the desired gemstone mounting. It is time consuming because material is removed from each of the 4 to 6 prongs (depending upon the type of setting) one at a time. The process is very exacting because care must be taken to adjust the inset or edge formed in each prong to the same depth and approximate width to maintain the strength and aesthetics of the setting.
Once the seat is prepared, the gemstone is placed in the setting and the ends of the prongs extending above the girdle are bent over the outer edge of the stone. In bending the metal over the stone, especially with hard jewelry metals, care must be taken not to damage the stone. If the tools used for the bending procedure drive against the stone in any way then there is a risk of cracking the stone. At the same time, hard materials such as diamonds can deflect a misguided tool and cause it to strike the stone setter, causing injury and a corresponding loss of productivity.
It is very desirable to be able to produce a large number of seats for gemstones in a short amount of time and with a fairly low degree of skill in order to reduce costs and increase related profits and production rates. This is especially true where large numbers of similar or identical gemstones are mounted in identical settings in jewelry manufacturing operations. The degree of skill that is required for the setting has hampered development of cost effective large scale stone mounting operations. Merely working faster and in larger numbers leads to mistakes and inaccuracies that degrade the jewelry quality.
There have been devices made in an attempt to mechanize some of the stone mounting steps. One such device is an apparatus for swaging gem mounts as disclosed in U.S. Pat. No. 3,839,770, issued Oct. 8, 1974 to H. V. Favre. The Favre patent discloses a device that performs the closing, crimping, or swaging of claws over a stone placed in a clawed setting. While the device of Favre allows the setting of a stone by a less skilled individual, it does not address fine "pronged" jewelry settings. Claw type settings are generally used on inexpensive stones or jewelry such as in setting rhinestones on clothing articles. These settings are not cut to form a seat as previously described but are preformed with thin prongs that are easily bent over the top of a stone.
Therefore, problems still remain with mechanizing or automating the gemstone mounting process for fine jewelry settings in terms of preparing a properly dimensioned and centered seat, and swaging a stone in the center of the seat. These and related problems have prevented the development of faster, high precision, high quality, lower cost, gemstone mounting for large volumes of gemstones.